Researchers accidentally find industrial waste, orange peel material sucks mercury out of water

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Researchers at Flinders University have accidentally discovered a way to remove mercury from water using a material made from industrial waste and orange peel.

Mercury is a dangerous pollutant that can damage food and water supplies, affect the human nervous systems and is especially poisonous for children.

Synthetic chemist Dr Justin Chalker said his team initially set out to make a useful type of plastic or polymer made from something widely available.

"We ended up settling on sulphur because it's produced in 70 million tonnes per year by the petroleum industry as a by-product, so there are not very many uses for it, and limonene is produced in 70,000 tonnes per year and so it's relatively cheap," he said.

"It literally grows on trees."

A block of the sulfur-limonene polysulfide: a polymer synthesised entirely from industrial by-products

The plastic-like substance they created is made entirely from sulphur and limonene, industrial waste products that are widely available but unused around the world.

"We take sulphur, which is a by-product of the petroleum industry, and we take limonene, which is the main component of orange oil, so is produced in large quantities by the citrus industry, and we're able to react them together to form a type of soft red rubber, and what this material does is that it can grab mercury out of the water," Dr Chalker said.

"So we are taking waste material and making a polymer from it that can remove mercury from water."

Because the material needed to make the polymer is so inexpensive, large quantities can be deployed at a site of contamination, in rivers, lakes and other waterways.

"We've also done toxicity studies to make sure that the polymer itself is not harmful to the environment so that gives us hope that we'll be able to commercialise and actually use this in the environment," Dr Chalker said.

The substance could be used to literally suck up mercury at sites where it is contaminating water.

"We also are thinking about using it as a coating to line pipes and other devices that are used to transport water or it could be used as part of a water filtration device," Dr Chalker said.

The substance changes colour when it comes into contact with and absorbs mercury, which means it could also be used to detect whether waterways are polluted.

New substance could help solve potentially fatal disorder

Dr Jack Ng, who heads the risk assessment program for the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, said mercury's impact on humans could be devastating.

"When you talk about organic form of mercury, this neurological disorder, high doses can be fatal... [it's] particularly a problem in younger generation children and its neurological disorders and that's a major concern," he said.

Dr Ng sees big potential for this new substance.

"From what the briefing describes it seems to be a promising product, typically for mercury in water or in aqueous form it can act with this polymer material," he said.

Jon Miller, the managing director of environmental remediation company the Remediation Group, said there was a significant need for a solution to mercury contamination.

"In particular there is a significant amount of mercury in bio-solids, which is the end product of sewerage treatment processes," Mr Miller said.

"There are large stock piles of bio-solids that contain mercury certainly here in Melbourne and if there is a way of being able to remove the mercury then it could be used for either energy generation of agricultural applications.

Max Worthington and Dr Justin Chalker (L to R) found the material's mercury-removing potential by accident.

"So that comes to mind as being an obvious first starter if it can be proved that this process genuinely works."

The Flinders University project findings are being published today in the German Chemical Society journal Angewandte Chemie International Edition. 

by Lucy Carter / via ABC

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